Abstract

MICROBIAL COMMUNITY STRUCTURE AND FUNCTION ON SINKING PARTICES AT STATION ALOHA

The main goal of this study was to better define the microbial taxa and biochemical processes involved in carbon and energy cycling on sinking particles collected at different depths in the North Pacific Subtropical Gyre at station ALOHA. We used metagenomic approaches to examine microbial communities associated with sinking particles that were collected using sediment traps at four depths between 150 meters and 500 meters during 2012 and 2013. Across all studied depths, there was a pronounced enrichment of Alteromonas species in “live” traps in which microbial growth and processing continued until trap recovery. In contrast, “dead” traps containing fixative were dominated by Vibrio species at shallower depths (150-300 meters) and Arcobacter at 500 meters. Archaea showed little variation across depths and solution types, all traps being dominated by either Marine Group II Euryarchaeota, or Thaumarchaeota representatives. Metagenomic and metatranscriptomic analyses of microbes associated with sinking particles revealed the diversity and functional attributes of microbes on sinking particles, and provide new insight into this important component of the marine carbon cycle.